Dunn County produced water spill far exceeds initial report

Earthen dams covered in a plastic liner have been installed near the site of a brine spill in Dunn County reported in October. The North Dakota Department of Environmental Quality says a pipeline operated by Marathon Oil Co. leaked more than 1.4 million gallons of brine. (Contibuted photo via Bismarck Tribune)

MANNING, N.D. — A pipeline that leaked produced water in western North Dakota's Dunn County last month released 1.4 million gallons of brine — far more than originally estimated, a state agency said Friday, Nov. 22.

The North Dakota Department of Environmental Quality announced that it had received an updated estimate on a Marathon Oil produced water spill about a mile and a half northeast of Manning on Oct. 2. According to an investigation into the incident, 32,826 barrels, or 1,378,692 gallons, were discharged.

“We got out to the site and when we looked at it, everyone kind of knew it’d be bigger than (Marathon) initially estimated,” Bill Suess, spill investigation program manager for the state agency, told The Press on Friday. “They based their calculations on the surface impact they saw at the time, but with just the concentration we had seen in the stock pond, we knew it was going to be bigger — we just didn’t know how big.”

As for the discrepancy in Marathon Oil’s estimates for the volume of the spill, Suess claims that, given that the pipeline was buried and that produced water spills are often harder to detect than crude oil, since most of the effects are subsurface, there is no way that Marathon could have been definitive that early in the investigation.

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“We would have never gotten an accurate number,” the investigation manager said. “Though I don’t anticipate a major overall long-term negative effect.”

The spill site is near a small creek flowing into the Knife River about a mile downstream of a stock pond. No impacts have been detected in the Knife River, the Department of Environmental Quality said in a news release.

Produced water is a toxic and often hard to detect natural byproduct of crude oil extraction. With sodium chloride, the same composition that can be found in regular table salt and ocean water, as its main ingredient, the effects on plant and aquatic life when exposed to produced water can be detrimental.

“I’d rather deal with a crude oil spill on land, than a salt water spill,” Suess said.

After crude oil is extracted, the salt water is separated from the fuel and sent through a gathering line to a salt water disposal facility. From there, the water is reinjected back into the ground.

Despite the spill, as well as the astounding discrepancy in their estimates, Suess and other Dunn County officials, said that the oil company will do the right thing.

“I would say that Marathon’s actually doing a good job,” Suess told The Press. “They’ve been on top of the clean up, they’ve got the Knife River protected, the cattle in the area are protected. They’re continuing to monitor and ensure the Knife River is safe.”

Denise Brew, emergency services manager for Dunn County, told The Press that Dunn County and Marathon have had a “great line of communication.”

“This incident isn’t a matter of somebody doing something wrong; it’s a combination of a wet season, the weather and the landscape of Dunn County,” Brew said.

A Marathon Oil pipeline that leaked produced water northeast of Manning last month released far more of the brine than originally estimated, a state agency said Friday, Nov. 22. Photograph by James Miller/ The Dickinson Press.